Bug 149968 – Web pages with unscalable viewports shouldn't have a single tap delay

• Component: WebKit Misc.
• Status: RESOLVED FIXED

[Wenson Hsieh]

When a page has an unscalable viewport (for instance, user-scalable = no or minimum-scale = 1, maximum-scale = 1) we should not have to wait 350 ms for the double tap gesture recognizer to fire.

[Wenson Hsieh]

<rdar://problem/23054453>

[Alexey Proskuryakov]

Can we just get rid of unscalable web pages instead? These are the worst.

[Wenson Hsieh]

Created attachment 262834 [details]
Patch

[Wenson Hsieh]

Created attachment 262864 [details]
Patch

[Simon Fraser (smfr)]

Comment on attachment 262864 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=262864&action=review

> Source/WebKit2/UIProcess/ios/WKContentViewInteraction.mm:2266
> +- (void)_setDoubleTapGesturesEnabled:(BOOL)enabled
> +{
> +    if (enabled && ![_doubleTapGestureRecognizer isEnabled]) {
> +        // The first tap recognized after re-enabling double tap gestures will not wait for the
> +        // second tap before committing. To fix this, we use a new double tap gesture recognizer.
> +        [self removeGestureRecognizer:_doubleTapGestureRecognizer.get()];
> +        [_doubleTapGestureRecognizer setDelegate:nil];
> +        [self _createAndConfigureDoubleTapGestureRecognizer];
> +    }
> +    [_doubleTapGestureRecognizer setEnabled:enabled];
> +}

Why can't we do this when we adjust the UIScrollView zoom scales? We know if it's zoomable there.

> Source/WebKit2/WebProcess/WebPage/ios/WebPageIOS.mm:252
> +    bool viewportIsUserScalable = userCanScaleViewport(m_viewportConfiguration);
> +    if (viewportWasUserScalable != viewportIsUserScalable)
> +        send(Messages::WebPageProxy::ViewportUserScalableDidChange(viewportIsUserScalable));

This should not be a new message (if it's needed at all); it should be in the transaction.

[Wenson Hsieh]

Created attachment 263057 [details]
Patch

[WebKit Commit Bot]

Comment on attachment 263057 [details]
Patch

Clearing flags on attachment: 263057

Committed r191072: <http://trac.webkit.org/changeset/191072>

[WebKit Commit Bot]

All reviewed patches have been landed.  Closing bug.

[Patrick H. Lauke]

Great stuff and fast work there. Interesting to note that my proposal to tackle this has been sitting in limbo for 2 years https://bugs.webkit.org/show_bug.cgi?id=122212